Update clang-format version

[kodebach]

clang-format version 15 has been released. We still use version 13 (see scripts/dev/reformat-c). At some point we should update. This will probably involve a bigger reformatting PR.

[mpranj]

Clang format 14 is not yet on Debian Sid, which we use in the CI for the formatting check…Should we switch to a different container?

[kodebach]

At least the online package search says that the current clang-format on Sid is version 14: https://packages.debian.org/sid/clang-format

And there is also a separate package for version 15: https://packages.debian.org/sid/clang-format-15

Should we switch to a different container?

Might be a good idea to use a separate container for formatting and similar checks that contributors may want to run locally (spelling, release notes, clang-tidy #4517, etc.). Keeping that container small would make that much easier.

The Alpine Linux Package for clang-format is also already on version 15.0.2 (released this week). I think a small alpine container would be ideal here.

[markus2330]

Switching clang-format is a task shortly before a release (to minimize necessary rebasing of PRs), so let us have a look at the situation when it is time.

[kodebach]

Could also be done right after mergingnew-backend. But I mainly created the issue so we don't forget to do it, not because it is urgent.

[markus2330]

It cannot really be forgotten totally. I don't think we need to create issues as long as there is no depreciation warning or it is getting difficult to install. If we skip some releases, we have less effort.

[kodebach]

Honestly please answer this question: "WHY do you hate issues so much?" Having an issue clearly signals there is something to be done. Especially, in a case like this, where it can't be solved immediately.

Waiting until there is a problem is not even a good solution here, because then the change would be urgent and can't just be done when it is convenient.

[markus2330]

Updating clang is done regularly by @mpranj before the releases, no issues are needed for this. Release notes are our way to communicate that such a change happened.